Tannic acid purification from pomegranate peel via tannic acid imprinted particle-embedded cryogel column.

Tannic acid (TA) is hydrolysable tannin found in the leaves and bark of many herbaceous and woody plants. Purification of TA is important due to its antibacterial, antihistaminic, antioxidant, antimutagenic and antitussive properties. In this study, 2-hydroxyethyl methacrylate-based TA-imprinted particle embedded cryogel (TA-MIP) was synthesized to purify TA from pomegranate peel. Furthermore, non-imprinted particle embedded cryogel (NIP) was synthesized to determine specific adsorption properties of TA-MIP, and control cryogel was synthesized without embedding procedure. The synthesized cryogel columns were characterized via scanning electron microscopy, Brunauer-Emmett-Teller surface area analysis, fourier-transform infrared spectroscopy, and swelling studies. Particle-embedding procedure resulted in a significantly higher specific surface area of particle-embedded columns (TA-MIP and NIP, 29 m2/g and 25 m2/g, respectively) than the specific surface area of control cryogel (9 m2/g). Adsorption studies were performed from aqueous solutions and maximum TA adsorption was found to be 34.4 mg/g for TA-MIP, 3.9 mg/g for NIP, and 2.8 mg/g for control cryogel. Within the scope of selectivity study, it was demonstrated that the synthesized columns have a high selectivity for TA against gallic acid (GA) and quercetin (QCT). Finally, purification of TA directly from pomegranate peel extract was studied and results were confirmed by HPLC. Furthermore, it has been proven that TA-MIP cryogel columns can be repeatedly used up to ten-times without any remarkable reduction in the TA adsorption amount.

Enhanced laccase separation from fermentation medium using cryogel columns.

The laccase enzyme family belongs to the oxidoreductase enzyme class and is one of the most commercially valuable enzymes that catalyzes the oxidation of one electron of a wide range of phenolic compounds. Separation and purification of laccases are crucial for industry since they play an important role in dye decolorization, biodegradation and food processing. Therefore, developing effective, high yielding and cost-effective methods for laccase production is vital. In this study, it was aimed to prepare cryogel columns for laccase purification following the bioproduction of laccase via Aspergillus niger. 2-hydroxyethyl methacrylate based cryogels were synthesized in the presence of 1-vinylimidazole as the affinity ligand and characterized by swelling tests, Brunauer-Emmett-Teller surface area measurement and scanning electron microscopy analysis. Surface area and water uptake ratio of cryogel columns were 35 m2/g and 93 %, respectively. The effect of pH, equilibrium laccase concentration, flow rate, interaction time and temperature on laccase adsorption were examined. The purification factor was calculated as 10.53 under optimum conditions and the enzyme recovery was found to be 86.7 % from fermentation medium. Current study revealed that laccase purification using cryogels following filtration of fermentation medium could be a promising candidate for industrial applications with eliminating the need for complex chromatographic steps.

AFB1 recognition from liver tissue via AFB1 imprinted magnetic nanoparticles.

Aflatoxins (AFs) are produced mainly by Aspergillus flavus and Aspergillus parasiticus and aflatoxin B1 (AFB1) is one of the most toxic aflatoxins with its carcinogenic property. AFB1 recognition from samples is very important and PHEMA based AFB1 imprinted magnetic nanoparticles (magAFB1-MIPs) were synthesized for the selective AFB1 recognition from liver tissue. The AFB1-MIPs were synthesized in different mole ratios and NIPs were synthesized for control. Characterization studies of magAFB1-MIPs and NIPs were carried out by swelling tests, surface area measurements, scanning electron microscopy and particle size analysis. The surface area was found as 117 m2/g and the size of the nanoparticles were found as 483 nm in diameter. The percentage yield of polymerization was calculated as 98 % and the template (AFB1) removal ratio from the magAFB1-MIPs was calculated as 91 %. The maximum adsorbtion capacities were calculated as 427.57 ng g-1 for magAFB1-MIPs and 44.6 ng g-1 for magNIPs. Selectivity tests showed that magAFB1-MIPs adsorb AFB1 1.74, 4.40, 2.46 times selective than that of AFB2, AFG1 and AFG2 molecules, respectively. AFB1 removal amount from AFB1 spiked liver tissue was satisfactory and recorded as 10.4 ng g-1 and 54.8 ng g-1 for 2 ng g-1 and 10 ng g-1 spiked liver tissue samples, respectively. AFB1 adsorption amount decrease was found negligible for 10 consecutive adsorption-desorption repeats in reusability study.

Determination of mold contamination using ergosterol imprinted particles.

Ergosterol is a key biochemical marker for fungal mycelial growth. In this study, molecularly ergosterol imprinted particles (Erg-MIPs) were newly synthesized for the selective detection of ergosterol in mold samples. Erg-MIPs were characterized via scanning electron microscopy, swelling studies, and surface area measurements. Maximum selective ergosterol adsorption achieved as 28.50 mg/g Erg-MIP. Selectivity studies showed that Erg-MIPs adsorbed Erg 2.01 and 3.27 times higher than that of cholesterol and stigmasterol, respectively. Erg adsorption from Aspergillus niger was found as 23.87 mg/g. Reusability of Erg-MIPs was studied and decrease in Erg adsorption capacity of the particles was negligible (3%). Erg-MIPs are good affinity materials for the selective Erg detection from food samples, prior to use in food industry.

A conceptual framework for the collection of food products in a Total Diet Study.

A total diet study (TDS) provides representative and realistic data for assessing the dietary intake of chemicals, such as contaminants and residues, and nutrients, at a population level. Reproducing the diet through collection of customarily consumed foods and their preparation as habitually eaten is crucial to ensure representativeness, i.e., all relevant foods are included and all potential dietary sources of the substances investigated are captured. Having this in mind, a conceptual framework for building a relevant food-shopping list was developed as a research task in the European Union's 7th Framework Program project, 'Total Diet Study Exposure' (TDS-Exposure), aimed at standardising methods for food sampling, analyses, exposure assessment calculations and modelling, priority foods, and selection of chemical contaminants. A stepwise approach following the knowledge translation (KT) model for concept analysis is proposed to set up a general protocol for the collection of food products in a TDS in terms of steps (characterisation of the food list, development of the food-shopping list, food products collection) and pillars (background documentation, procedures, and tools). A simple model for structuring the information in a way to support the implementation of the process, by presenting relevant datasets, forms to store inherent information, and folders to record the results is also proposed. Reproducibility of the process and possibility to exploit the gathered information are two main features of such a system for future applications.

TDS exposure project: relevance of the total diet study approach for different groups of substances.

A method to validate the relevance of the Total Diet Study (TDS) approach for different types of substances is described. As a first step, a list of >2800 chemicals classified into eight main groups of relevance for food safety (natural components, environmental contaminants, substances intentionally added to foods, residues, naturally occurring contaminants, process contaminants, contaminants from packaging and food contact materials, other substances) has been established. The appropriateness of the TDS approach for the different substance groups has then been considered with regard to the three essential principles of a TDS: representativeness of the whole diet, pooling of foods and food analyzed as consumed. Four criteria were considered for that purpose (i) the substance has to be present in a significant part of the diet or predominantly present in specific food groups, (ii) a robust analytical method has to be available to determine it in potential contributors to the dietary exposure of the population, and (iii) the dilution impact of pooling and (iv) the impact of everyday food preparation methods on the concentration of the substance are assessed. For most of the substances the TDS approach appeared to be relevant and any precautions to be taken are outlined.